/// <summary>
/// Gets the current Parent Entity value from the database,
/// that this Child Entity instance is bound to.
/// </summary>
/// <returns></returns>
public TEntity Fetch()
{
// Get our Table Mapping
Type objType = typeof(TEntity);
TableMapping table = EntityCache.GetTableMap(objType);
// Connect to the SQLite database, and prepare the query
using (SQLiteContext context = new SQLiteContext(ConnectionString))
{
// Open the connection
context.Connect();
// Build the SQL query
SelectQueryBuilder builder = new SelectQueryBuilder(context);
builder.From(table.TableName).SelectAll().Take(1);
builder.WhereStatement = Statement;
// Execute the Data Reader
using (SQLiteCommand command = builder.BuildCommand())
using (SQLiteDataReader reader = command.ExecuteReader())
{
// If we have rows, add them to the list
if (reader.HasRows)
{
// Return each row
reader.Read();
return(context.ConvertToEntity <TEntity>(table, reader));
}
else
{
return(null);
}
}
}
}
/// <summary>
/// Lazy loads the child entities of a foreign key constraint
/// </summary>
public IEnumerator <TChildEntity> GetEnumerator()
{
// Grab table mappings
TableMapping parentTable = EntityCache.GetTableMap(typeof(TParentEntity));
TableMapping childTable = EntityCache.GetTableMap(typeof(TChildEntity));
// Create the SQL Command
using (SQLiteContext context = new SQLiteContext(ConnectionString))
{
// Open the connection
context.Connect();
// Begin a new Select Query
SelectQueryBuilder query = new SelectQueryBuilder(context);
query.From(childTable.TableName).SelectAll();
// Grab the foreign key constraints
var fkinfos = childTable.ForeignKeys.Where(x => x.ParentEntityType == parentTable.EntityType);
foreach (ForeignKeyConstraint fkinfo in fkinfos)
{
// Append each key => value to the query
for (int i = 0; i < fkinfo.ForeignKey.Attributes.Length; i++)
{
string attrName = fkinfo.ForeignKey.Attributes[i];
string parentColName = fkinfo.InverseKey.Attributes[i];
// Add column expression
AttributeInfo attribute = parentTable.GetAttribute(parentColName);
query.Where(attrName, Comparison.Equals, attribute.Property.GetValue(Entity));
}
// Create a new clause, to seperate by an OR
query.WhereStatement.CreateNewClause();
}
// Create command
using (SQLiteCommand command = query.BuildCommand())
using (SQLiteDataReader reader = command.ExecuteReader())
{
// If we have rows, return each row
while (reader.Read())
{
yield return(context.ConvertToEntity <TChildEntity>(childTable, reader));
}
// Cleanup
reader.Close();
}
}
}
